Topological structure in the perception of apparent motion

Not only translations and rotations, but also intriguing 'plastic deformations' are observed in apparent motion. What kinds of invariants does the visual system depend on during these transformations to determine that two figures of different shapes nevertheless represent the same object? Experiments are reported in which seven pairs of stimuli with topological differences were used. The evidence suggests that topological invariants may be used in the perception of apparent motion. In spite of variations in other factors, such as brightness, spatial frequency, terminators, etc, subjects displayed a strong preference for motion from a central figure to a figure with the same topological invariants. The results emphasize the importance of topological structure in figure perception.

Alkaline phosphatase and OmpA protein can be translocated posttranslationally into membrane vesicles of Escherichia coli

We previously described a system for translocating the periplasmic enzyme alkaline phosphatase and the outer membrane protein OmpA into inverted membrane vesicles of Escherichia coli. We have now optimized and substantially improved the translocation system by including polyamines and by reducing the amount of membrane used. Under these conditions, efficient translocation was seen even posttranslationally, i.e., when vesicles were not added until after protein synthesis was stopped. This was the case not only with the OmpA protein, which is synthesized by free polysomes and hence is presumably exported posttranslationally in the cell, but also with alkaline phosphatase, which is synthesized only by membrane-bound polysomes and has been shown to be secreted cotranslationally in the cells. Prolonged incubation rendered the precursors inactive for subsequent translocation. Posttranslational translocation was impaired, like cotranslational translocation, by inhibitors of the proton motive force and by treatment of the vesicles with protease. Since it appears that E. coli can translocate the same proteins either cotranslationally or posttranslationally, the cotranslational mode may perhaps be more efficient, but not obligatory, for the secretion of bacterial proteins.

The influence of halothane and isoflurane on pulmonary collateral ventilation

The effects of halothane and isoflurane on hypocapnic increases in pulmonary collateral resistance were studied in dogs. A bronchoscope with a double lumen catheter in the suction port obstructed a peripheral airway and allowed gas to flow out of the isolated segment of lung only via collateral channels. The collateral gas flow (Vcoll) was measured with a flowmeter and delivered through one lumen of the catheter, while the other lumen measured distal pressure (Pb). At FRC, the resistance to collateral ventilation (Rcoll) was calculated as Rcoll = Pb/Vcoll. The rest of the lung was ventilated with air, while air (hypocapnia), 10% CO2 in air, or air and halothane or isoflurane were delivered to the isolated segment. A measurement of resistance was made after 4 min of test gas flow. For each segment, when air replaced 10% CO2, the average increase in Rcoll was calculated and called Rmax. When 10% CO2 in air was infused into segments the mean Rcoll (n = 50) was 0.0196 +/- 0.0022 cmH2O X ml-1 X min. This increased to 0.0285 +/- 0.0031 cmH2O X ml-1 X min (mean +/- E) when air was infused, a mean increase in resistance of 52 +/- 3%. When halothane or isoflurane was added to air the hypocapnic increase in Rcoll was attenuated with a 50% decrease at 1.3% (1.4 MAC and 0.8 MAC, respectively). These two inhalational anesthetics reduce active changes in the flow resistance to collateral ventilation. When collateral resistance acts to adjust ventilation perfusion deviations, this action of halothane and isoflurane may make this regulation less effective.

Cell to cell transmission of the "priming" effect on the induction of human fibroblast interferon

Human fibroblast cells remain primed for IFN-beta 1 synthesis for at least 18 days after the removal of IFN-beta 1, to the same extent as cells primed shortly before induction. The maximal effect of priming is observed in cells that are treated with IFN at low cell density and are subsequently allowed to undergo several divisions. This observation suggests that the information for priming is propagated from cell to cell upon cell division. A diminished priming effect is observed after cells undergo more than three divisions in culture, suggesting a dilution of the mediator responsible for the transmission of the effect. It was not possible to demonstrate intercellular communication of the priming effect by a mediator found in the medium or by cell to cell contact. Observation that priming persists in cells for 18 days in the absence of detectable levels of IFN in the medium, but virus-resistance declines after three days supports the previous suggestion for different mechanisms involved in these two IFN-induced phenomena.

A human IFN-beta 1 gene deleted of promoter sequences upstream from the TATA box is controlled post-transcriptionally by dsRNA

Induction of IFN-beta 1 RNA was studied in the mouse cell line SR117-21E transformed by a BPV episome containing the human IFN-beta 1 gene deleted of promoter sequences upstream from position -40. Nuclei isolated from these cells synthesize constitutively IFN-beta 1 RNA from the partially deleted promoter. The IFN-beta 1 RNA synthesized by nuclei of uninduced SR117-21E cells is similar to that made by nuclei of poly(rI):(rC)-induced cells, but does not accumulate and hence no IFN is produced unless the cells have been treated either by ds RNA or by cycloheximide. We conclude that the IFN-beta 1 gene has, in addition to the transcription control due to upstream promoter sequences, an additional post-transcriptional control acting on mRNA accumulation and linked to sequences close to the TATA box and RNA start site. Both controls are relieved by ds RNA.

Efficient constitutive production of human fibroblast interferon by hamster cells transformed with the IFN-beta 1 gene fused to an SV40 early promoter

The coding sequence of the human interferon (IFN)-beta 1 gene, fused 60 bp downstream from the RNA start site of the SV40 early gene, was transfected into dihydrofolate reductase (DHFR)-deficient Chinese hamster ovary (CHO) cells together with a selectable DHFR gene. Most transformants continuously secreted IFN-beta 1 into the medium. Induction did not stimulate expression of the fused SV40-IFN-beta 1 gene. The role of the SV40 promoter was verified by transforming cells with the unmodified human IFN-beta 1 gene, or by the IFN-beta 1 coding region fused to another poly(rI):(rC)-inducible gene. In these cases, the transformants showed strictly inducible (not constitutive) IFN secretion. By selection for methotrexate resistance, CHO clones with a 10-20-fold amplification of the SV40-IFN-beta 1 DNA were obtained. Such clones constitutively produce up to 350,000 units IFN/ml per 10(6) cells/24 hr, i.e., over 10 times more than fully induced human fibroblasts. In continuous culture with daily changes of medium, accumulation of IFN-beta 1 is constant at a rate of 300,000 molecules per cell/hr. Batches of up to 16 mg of IFN-beta 1 produced by the transformed CHO cells were purified to homogeneity by affinity chromatography on monoclonal antibodies. This IFN appears identical in size, activity, and immunospecificity to the native human IFN-beta 1 glycoprotein.

Time course and responses of sustained hypoxic pulmonary vasoconstriction in the dog

The stability of the pulmonary blood pressure and flow response to alveolar hypoxia (hypoxic pulmonary vasoconstriction or HPV) was studied in six pentobarbital anesthetized, mechanically ventilated open-chested dogs. Aortic and left pulmonary artery blood flows; systemic and pulmonary arterial, central venous, left atrial, and airway pressures; hemoglobin; arterial and mixed venous blood gases were measured. The right lung was ventilated continuously with 100% oxygen, while the left lung was ventilated alternately with 100% O2 ( prehypoxia control phase), an hypoxic gas mixture containing 4% O2, 3% CO2, balance N2 for 4 h, or 100% O2 (post-hypoxia control phase). Hypoxic ventilation of the left lung resulted in an immediate and sustained decrease in left lung blood flow (QL%) from 39.0 +/- 1.8% (mean +/- SE) to 9.9 +/- 3.6% at 15 min of hypoxic ventilation. QL% remained decreased and did not vary significantly during the 4 h of hypoxia. Venous admixture correspondingly was increased and PaO2 decreased by hypoxic ventilation and did not vary significantly during the 4 h of hypoxia. All variables returned to control levels upon reestablishing ventilation with 100% O2. While the maximal reduction in QL% with left lung hypoxic ventilation was identical to that observed during atelectasis previously in our laboratory, the time course of the response was different. The response to hypoxia was maximal by 15 min, however, QL% decreased more slowly during atelectasis, where the maximal reduction was observed by 60 min. The present study therefore demonstrated that hypoxic ventilation of the left lung yielded an immediate and sustained decrease in left lung blood flow for 4 h. The stability of the HPV response probably was accounted for by the lack of such confounding factors as respiratory alkalosis, severe systemic hypoxemia, and increased cardiac output.

Clinical and immunopathologic study of mesangial IgM nephropathy: report of 41 cases

Forty-one out of 408 cases (or 10%) of primary glomerular disease had diffuse fine granular to arc-like short linear mesangial deposits of IgM by direct immunofluorescence. The IgM deposition was accompanied by C1q and/or C4 in the same locality in 29 cases, by C3 in 10, and by trace amounts of IgA in 6. Properdin-factor B was not detected. Fine granular electron dense deposits of low density were detected in the mesangium in all 41 cases by electron microscopy, usually as a discrete granular or arc-like pattern beneath the mesangial glomerular basement membrane and correlated well with the immunofluorescence findings. An immune complex disease with complement activation via the classical pathway is suggested. The ages of the patients varied from 2 to 58 years (average 23.8 years). A male predominance of 2.2:1 was identified. Serum IgM level was elevated in 46.7% of the cases. The majority (87.8%) of the cases manifested a nephrotic syndrome or relapse at time of biopsy, and the remaining cases experienced persistent or intermittent proteinuria. Among the 36 nephrotic patients, 22 cases (61.1%) demonstrated complete remission with steroid therapy, 9 cases (25%) were resistant, and 5 cases (13.9%) had partial remission. Complete and partial remissions were later achieved with cytotoxic drugs or methylprednisolone pulse therapy in 3 and 4 cases respectively in the steroid resistant patients. Frequent relapses occurred during the course in 22 out of 32 cases (68.8%) who had experienced complete or partial remission. Follow-up study after biopsy demonstrated that sustained complete remission was achieved with prednisolone with or without cytotoxic drugs and pulse therapy in only 14 (42.4%) of the 33 nephrotic cases who had been followed up for longer than 6 months, and six of them had had previous relapses. Pathologically, 56.1% of the patients showed mild to moderate increase in mesangial matrix and cellularity. Focal and segmental sclerosis was demonstrated in four cases (9.8%). However, minimal glomerular change was also common (34.1%). The patients with minimal change seemed to have a higher complete remission rate than patients with more evident glomerular alterations, although the difference was not statistically significant. This clinical and immunopathological study suggests that mesangial IgM nephropathy is an important disease in Taiwan, with a variable response to treatment and frequent relapses.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of the method of re-expansion of atelectatic lung upon the development of pulmonary edema in dogs

An endobronchial tube was used to separately ventilate each lung in anesthetized dogs, and absorption atelectasis was then induced in the left lung and maintained for 3 1/2 h. The left lung was partially re-expanded by ventilation at normal tidal volumes for 10 min, and then completely re-expanded by manual hyperinflation. This delayed re-expansion was associated with an extravascular water content significantly greater than that of the right lung. A previous study demonstrated no increase in the ratio of left to right lung water content after 3 h of atelectasis alone and a significant increase after immediate hyperinflation. Delayed re-expansion produces significantly different results, and it is therefore concluded that the method of lung re-expansion influences the development of pulmonary edema after atelectasis.

Cycloheximide induces expression of the human interferon beta 1 gene in mouse cells transformed by bovine papillomavirus-interferon beta 1 recombinants

Mouse cells transformed by a bovine papillomavirus recombinant vector containing the human interferon (IFN) beta 1 (IFN-beta 1) gene could be induced to produce human as well as mouse IFNs. The optimal conditions for induction of human IFN and of its mRNA in these transformants resembled those needed for mouse IFN: high concentrations of DEAE-dextran and low concentrations of polyriboinosinic acid-polyribocytidylic acid. Superinduction by inhibitors of protein synthesis which strongly stimulate IFN-beta 1 induction in human cells had only a small effect on human IFN induction in bovine papillomavirus IFN-beta 1-transformed mouse cells. In contrast, cycloheximide without double-stranded RNA could induce significant levels of human IFN in the bovine papillomavirus IFN-beta 1 mouse transformants. After cycloheximide treatment, these cells contained IFN-beta 1 mRNA whose 5' ends originated in the authentic start site of the human IFN-beta 1 gene, as shown by S1 nuclease mapping. The transferred human gene, propagated extrachromosomally in the mouse cells, was, therefore, inducible under conditions different from those in human cells. The results also confirmed that the inhibitor of protein synthesis, cycloheximide, can induce expression of a human IFN gene.

Expression of human interferon genes using the recA promoter of Escherichia coli

Interferon beta 1 and three alpha-interferon genes were cloned on Eco RI fragments isolated from a human genomic library into the Eco RI site of a plasmid containing the recA promoter of E. coli. Expression of interferon activity from cells carrying these plasmids was nalidixic acid inducible. The alpha-interferon genes were expressed only when in the same transcriptional orientation as the recA promoter while the beta 1 interferon gene was expressed in either orientation. Interferon activity was also inducibly expressed from the recA promoter in cells containing a plasmid carrying a fusion of the recA gene with the beta 1 interferon gene. This interferon activity was thirty-fold less sensitive to neutralization by polyclonal antibodies than authentic interferon, implying that the change near the amino terminus affects either antibody recognition or specific activity or both.

Topological structure in visual perception

Three experiments on tachistoscopic perception of visual stimuli demonstrate that the visual system is sensitive to global topological properties. The results indicate that extraction of global topological properties is a basic factor in perceptual organization.

Synthesis of human interferon beta 1 in Escherichia coli infected by a lambda phage recombinant containing a human genomic fragment

DNA from a human adult was fragmented by partial digestion with restriction endonuclease EcoRI and cloned in lambda Charon 4A. Clone C15, with a human DNA insert of 17 X 10(3) bases, was identified as containing a gene for the fibroblast interferon, interferon beta 1. Restriction mapping shows that this gene, located on a 1840-base EcoRI fragment, is not interrupted by introns. Moreover, we show that this human genomic DNA fragment is able to direct the synthesis of active human interferon beta 1 in Escherichia coli. Interferon activity of up to 7 X 10(6) U/l was recovered from phage lysates by chromatography on Cibacron blue--Sepharose, and had the same immunological properties and species specificity as interferon produced by human fibroblasts.

Preoperative and postoperative echocardiographic studies of pulmonic valvular endocarditis

The echocardiographic manifestations of pulmonic valvular endocarditis in a patient with underlying heart disease consisting of a ventricular septal defect and infundibular stenosis are reported. The abnormal shaggy echoes observed on the pulmonic valve were confirmed to be vegetations based on surgical and pathologic findings. This was further proven by the disappearance of the shaggy echoes after surgical excision of the vegetations. We conclude that echocardiograms can detect the presence and disappearance of pulmonic valvular vegetations, which may be of aid in the diagnosis of pulmonic valvular endocarditis.

Adenosine 3',5'-monophosphate (cAMP)-binding proteins and cAMP-dependent protein kinases in bovine adrenal cortical cell plasma membrane

A cAMP-binding protein and cAMP-dependent protein kinase have been identified and partially characterized in bovine adrenocortical plasma membranes. [3H]cAMP binding to the plasma membrane preparation demonstrates both high (Ka = 4.2 X 10(9) M-1) and low (Ka = 1.3 X 10(8) M-1) affinity binding sites. cAMP-dependent protein kinase was demonstrated using both bovine histone and endogenous substrates. The detergent-dependent solubilization characteristics of this cAMP-dependent protein kinase indicate that it is an integral membrane protein.

Neurofibrillary change on Guam

Distribution and occurrence of neurofibrillary change (NFC) in the brain were studied in 114 Guamanians who had neither amyotrophic lateral sclerosis (ALS) nor parkinsonism dementia (PD). Comparison was made with 28 Guamanians with ALS-PD and 53 non-Guamanians without ALS-PD. Search for NFC was made in 15 dogs and cats that lived on Guam. Most of the Guamanians without ALS-PD during and after middle age had NFC similar to that of Guamanians with ALS-PD but lesser in degree and extent of involvement. It is possible that the general population of Guam had been exposed to the unknown etiologic agent of ALS-PD during some previous period.

Steroid receptors in human renal carcinoma

Glucocorticoid- and androgen-binding receptors were demonstrated in cytosol of human renal cell carcinomas by the dextran-coated charcoal technique. Sedimentation studies using preparative ultracentrifugation indicated a 7 to 8 S binding component. None of the renal carcinoma cells tested contained detectable estrogen receptors and a few samples had a very low but demonstrable progestin receptor level. In the normal kidneys tested, cytoplasmic components that bound only androgen could be detected. Competition studies showed that progestin competed for the glucocorticoid receptor sites in all the renal tumors tested, whereas diethylstilbestrol and testosterone were weak or not competitive. It is suggested that the response of some patients with renal carcinoma to high doses of progesterone or androgens could be explained by the ability of these hormones to block the activity of glucocorticoid receptors, which might be involved in tumor growth.

A testicular tumor with gingival metastasis

Testicular tumors comprise approximately 1 percent of all malignant neoplasms in the male. However, they are one of the more common malignant diseases of adolescent and young adult males. An unusual case of a testicular neoplasm in a 23-year-old man exhibiting gingival metastasis is presented.